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A Bat Fungus on the March

Bats infected with white nose syndrome.Credit United States Geological Survey

A deadly bat fungus has spread to three caves in Cumberland Gap National Historic Park in Virginia, park officials have confirmed.

The fungus, known as white nose syndrome, has killed millions of bats in the Northeast and Midwest since it was discovered in a cave in New York State in 2006. Late last month, it was confirmed to have spread as far west as Onondaga Cave State Park in Missouri

Meanwhile, it it is turning up in additional caves to the east as well. At Cumberland Gap, “three out of 30 caves in the park tested positive for the disease, and we know that bats travel between all of the caves, so that’s not good,” said Carol Borneman, a ranger at the park, which straddles parts of Kentucky and Tennessee as well as Virginia.
White nose syndrome was also recently confirmed in Kentucky’s Mammoth Cave National Park.

While scientists scramble to better understand the disease, federal and local officials are alerting spelunkers and miners to clean their shoes and clothing so as to not accidentally spread the fungus while traveling, said Ann Froschauer, a spokeswoman for the federal Fish and Wildlife Service.

As for the perambulating bats themselves, there’s not much park officials can do. “The bats are moving it pretty quickly and efficiently on their own, and we don’t have any way we can prevent that spread,” Ms. Froschauer said.

Since the fungus was found in New York in 2006, genetic tests have shown that the spores are closely related to microbes found in Europe, suggesting that the disease was imported. Many European bats seem immune to the disease even though they are carrying the spores.

In North America, white nose syndrome has killed more than 5.5 million bats across 19 states and four Canadian provinces. The ecological consequences could prove significant: that number of bats would normally eat some 8,000 tons of insects each year, many of them pests that are harmful to agriculture and forests, scientists say.

The fungus threatens bats in several ways, including one that seems to parallel immune reconstitution inflammatory syndrome in AIDS patients, said Carol U. Meteyer, a wildlife pathologist for the United States Geological Survey.

The fungus generally attacks when a bat is hibernating and both its body temperature and immune system are depressed. When the bat wakes in the spring, its shocked immune system goes on a rampage, destroying healthy tissue and fungus alike.

Scientists have suggested that this is akin to the way that, after heavy doses of anti-retroviral therapy, the strengthened immune system in a human AIDS patient may over-respond to a pre-existing infection and damage healthy tissue.

“In both humans and bats, it’s an immune-suppressed individual who suddenly recovers their immune function, and their immune system overreacts and damages surrounding tissue as well as the fungus,” Dr. Meteyer said. She added that many infected bats had tears in their wings caused by their own immune response.

Bat mortality in caves and mines where the fungus has been present for more than a year exceeds 90 percent, scientists say. Most new cases of white nose syndrome are discovered during the winter, when the bats display symptoms of the disease like flying outside during daylight hours or are observed in caves to have fuzzy white growths around their snouts and on their wings.

The fungus also lives in cave soil, which stays cool year round, and afflicting bats appears to be incidental to its main function, which is breaking down organic matter, scientists say. Because the fungus does not need bats to survive, it can persist in caves and mines where bats have been completely wiped out. Scientists are working against the clock to determine whether some bat populations stand a better chance of avoiding the fungus by hibernating in parts of caves where spore concentrations are lower.

In the meantime, wildlife officials are advocating that more species of bats be considered for listing under the Endangered Species Act.

“White nose syndrome is here, and it’s moving really quickly,” Ms. Froschauer said. “We’ll hope that it won’t get any further west, but it probably will.”

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